The present invention is directed to the efficient utilization of heat which is ordinarily expelled with the flu gases from large scale furnaces such as blast furnaces, smelters and the like and to the efficient removal of all contaminates from the flu gases subsequent to the utilization of the heat but prior to the expulsion of the gases into the atmosphere.
For many years the hot effluent gases from blast furnaces, smelters and the like were passed through a conventional emission stack directly into the atmosphere. While some of the flu gases having a high BTU value were utilized as pipeline gas for subsequent burning, the heat carried by these gases as they left the furnace was ordinarily dissipated in an extremely wasteful manner. Since the advent of strict pollution controls, most companies have made an effort to remove the contaminates from the effluent gases prior to or during passage of the gases through the emission stack. If the gases pass through various scrubbers or other anti-pollution devices prior to being expelled into the atmosphere, the heat accompanying these gases as they leave the furnace is quickly dissipated during passage through the pollution control devices so that the temperature of the clean gases finally being expelled into the atmosphere is quite low.
In the refinement of metal ores a substantial amount of metal values are carried away with the effluent gases thereby decreasing the efficiency of the smelting operation. The use of electrostatic precipitators was prevalent long before the advent of pollution control for the purpose of capturing some of the metal values from the effluent gases. However, many of the ores were not amenable to electrostatic precipitation and a substantial amount of metal values were irretrievably lost during the smelting operation.